Analysis of the Correlation Between Tongue Fat and Retroglossal Obstruction in Patients with Obstructive Sleep Apnea

To investigate the impact of tongue fat on glossoptosis and lingual hypertrophy and the relationship between tongue fat and retroglossal obstruction in patients with obstructive sleep apnea (OSA).

This study enrolled 97 patients with moderate-to-severe OSA. All patients underwent standard diagnostic polysomnography (PSG) and a second PSG with a nasopharyngeal tube inserted (NPT-PSG). The NPT stents open the nasal, nasopharyngeal, and retropalatal airways, so the residual apnea-hypopnea index (NPT-AHI) specifically quantifies retroglossal obstruction. Patients were classified based on NPT-PSG and upper airway CT into three groups: non-retroglossal obstruction (non-RGO), glossoptosis (GLO), and lingual hypertrophy (LH). Three-dimensional CT reconstructions were used to assess tongue anatomy, including volume, fat volume, and fat percentage. Group differences in baseline traits and tongue measurements were analyzed. We further examined the relationship between tongue fat and RGO, and identified factors influencing RGO in OSA.

After adjusting for gender, age, and BMI, the LH group had larger tongue volume compared to the other two groups, whereas the GLO group had more tongue fat and a higher tongue fat percentage compared to the non-RGO group. Apnea-hypopnea index (AHI) for NPT-PSG (NPT-AHI) was positively correlated with tongue volume (r=0.349, P<0.001), tongue fat volume (r=0.368, P<0.001), and tongue fat percentage (r=0.281, P=0.006), and negatively correlated with LSaO₂ (r=-0.312, P<0.001). Multiple regression indicated tongue volume (β=0.264, P=0.005), tongue fat volume (β=0.271, P=0.002), and LSaO₂ (β=-0.285, P=0.006) were independent influencing factors of NPT-AHI.

Tongue fat volume is more strongly associated with glossoptosis, whereas overall tongue volume is more closely associated with lingual hypertrophy. Increased tongue volume, higher tongue fat content, and decreased LSaO₂ are associated with more severe retroglossal obstruction. Precise therapies targeting tongue fat may benefit OSA patients with RGO.